Method and apparatus for operating an EC-fuel pump

Abstract

A method for operating an electronically commutated fuel pump with an upstream fuel pump electronics unit of a motor vehicle, wherein the fuel pump is operated at a predefined speed, the method includes detecting a speed irregularity of the electronically commutated fuel pump, the speed irregularity being determined by examining the synchronicity between rotary field and rotor of the fuel pump, and switching over the speed of the electronically commutated fuel pump to a higher speed value than the predefined speed until a stable operation of the fuel pump without loss of synchronicity between rotary field and rotor of the fuel pump is achieved, the switchover of the fuel pump to the higher speed is performed by a predefined speed jump or is performed at predefined speed steps, the speed being increased until stable operation of the fuel pump is achieved.

The invention claimed is: 
     
       1. A method for operating an electronically commutated fuel pump under control of an upstream fuel pump electronics unit of a motor vehicle to avoid a speed irregularity indicative of a malfunction of the fuel pump resulting from lack of synchronicity of a rotor of the fuel pump occurring when a ratio of consumed and fed power falls below a threshold value, wherein pulse-width modulation is used to control rotational frequency of a magnetic rotary field generated in a drive of the fuel pump, wherein the rotational frequency is controlled separately from a strength of the magnetic rotary field, which defines maximum mechanical power available at the fuel pump drive, the fuel pump being operated at a predefined speed corresponding to stable operation of the fuel pump, the method comprising:
 monitoring an operating speed of the fuel pump to determine a speed deviation from the predefined speed, wherein the speed deviation indicates the speed irregularity indicative of the malfunction of the fuel pump resulting from lack of synchronicity of the rotor of the fuel pump, wherein the speed deviation is determined by examination of the synchronicity between the magnetic rotary field and the rotor of the fuel pump using the magnetic rotary field generated by stator coils in the pump drive; and 
 in response to the determination that the speed deviation from the predefined speed exceeds a predefined value, implementing an increase of the operating speed of the upstream fuel pump using a pump electronics unit to re-establish stable operation of the fuel pump resulting from rotor synchronicity, 
 wherein the control of the increase of the operating speed is performed by the upstream fuel pump electronics unit in one step by a predefined speed jump or is performed at predefined speed steps, the speed being increased until stable operation of the fuel pump is re-achieved as determined based on the speed deviation determined based on the examination of the synchronicity between the magnetic rotary field and the rotor of the fuel pump using the magnetic rotary field generated by stator coils in the pump drive, 
 wherein the upstream fuel pump electronics unit controls the electronically commutated fuel pump based on the detection of the speed irregularity indicative of a malfunction of the fuel pump resulting from lack of synchronicity of a rotor of the fuel pump to cause recovery of the rotor by the rotary field, maintain the higher operating speed for a specified period of time such that the operation of the electronically commutated fuel pump under control of the upstream fuel pump electronics unit of the motor vehicle avoids the speed irregularity indicative of the malfunction of the fuel pump resulting from lack of synchronicity of the rotor of the fuel pump occurring when the ratio of consumed and fed power falls below the threshold value to reduce a risk of loss of synchronicity, and 
 wherein the method further comprises the upstream fuel pump electronics unit controlling the electronically commutated fuel pump to lower the operating speed of the electronically commutated fuel pump again after a predefined time once an operating speed value for stable operation has been reached. 
 
     
     
       2. The method of  claim 1 , further comprising the upstream fuel pump electronics unit controlling the electronically commutated fuel pump to operate again at the predefined speed in response to the engine next being started. 
     
     
       3. An electronically commutated fuel pump for a motor vehicle, the fuel pump comprising:
 a fuel pump drive; and 
 an upstream fuel pump electronics unit for controlling operation of the electronically commutated fuel pump to avoid a speed irregularity indicative of a malfunction of the fuel pump resulting from lack of synchronicity of a rotor of the fuel pump occurring when a ratio of consumed and fed power falls below a threshold value, 
 wherein pulse-width modulation is used to control rotational frequency of a magnetic rotary field generated in the drive of the fuel pump, 
 wherein the rotational frequency is controlled separately from a strength of the magnetic rotary field, which defines maximum mechanical power available at the fuel pump drive, the fuel pump being operated at a predefined speed corresponding to stable operation of the fuel pump as determined based on the speed deviation determined based on the examination of the synchronicity between the magnetic rotary field and the rotor of the fuel pump using the magnetic rotary field generated by stator coils in the pump drive, 
 wherein a monitor is used to monitor an operating speed of the fuel pump to determine a speed deviation from the predefined speed, wherein the speed deviation indicates the speed irregularity indicative of malfunction of the fuel pump resulting from lack of synchronicity of the rotor of the fuel pump, 
 wherein the speed deviation is determined by the monitor by examination of the synchronicity between the magnetic rotary field and the rotor of the fuel pump using the magnetic rotary field generated by stator coils in the pump drive, 
 wherein the upstream fuel pump electronic unit is configured to, in response to the determination that the speed deviation from the predefined speed exceeding a predefined value, implement an increase of the operating speed of the upstream fuel pump to re-establish stable operation of the fuel pump resulting from rotor synchronicity, 
 wherein the control of the increase of the operating speed is performed by the upstream fuel pump electronics unit in one step by a predefined speed jump or is performed at predefined speed steps, the speed being increased until stable operation of the fuel pump is re-achieved, 
 wherein the upstream fuel pump electronics unit controls the electronically commutated fuel pump based on the detection of the speed irregularity indicative of a malfunction of the fuel pump resulting from lack of synchronicity of a rotor of the fuel pump to cause recovery of the rotor by the rotary field, maintain the higher operating speed for a specified period of time such that the operation of the electronically commutated fuel pump under control of the upstream fuel pump electronics unit of the motor vehicle avoids the speed irregularity indicative of the malfunction of the fuel pump resulting from lack of synchronicity of the rotor of the fuel pump occurring when the ratio of consumed and fed power falls below the threshold value to reduce a risk of loss of synchronicity, and 
 wherein the upstream fuel pump electronics unit controls the electronically commutated fuel pump to lower the operating speed of the electronically commutated fuel pump again after a predefined time once an operating speed value for stable operation has been reached. 
 
     
     
       4. The electronically commutated fuel pump of  claim 3 , wherein the upstream fuel pump electronics unit controls the electronically commutated fuel pump to operate again at the predefined speed in response to the engine next being started.